Study finds HPV, throat cancer link in both sexes

Throat cancer added to list of diseases caused by HPVStudy finds oral sex transmits virus in men and women

The virus that causes cervical cancer, the subject of heated debate in Austin, also sharply increases the risk of throat cancer for both men and women engaging in oral sex, according to a new study.

The study found that people who have had more than five oral-sex partners in their lifetime are 250 percent more likely to develop throat cancer than those who do not have oral sex. The cancer at one time was thought to be caused only by alcohol or tobacco.

"This study provides clear evidence that the human papillomavirus is a risk factor for throat cancer," said Dr. Maura Gillison, a Johns Hopkins oncologist and the study's senior author. "Health care providers need to know that these cancers can occur in people that don't smoke or drink."

Gillison stressed that the immune system usually clears HPV on its own. She said that just as few women with HPV in their genital tract get cervical cancer, most people with an oral infection probably will not go on to develop throat cancer.

But Gillison and others noted that the finding could explain why throat cancer, which includes the tonsils and back part of the tongue, is on the increase in nonsmokers in their 30s, 40s and 50s. Historically, it has occurred among heavy smokers and drinkers in their 60s and 70s. Those numbers are down.

The study could shift the debate to whether the HPV vaccine eventually should be required of both males and females. Not only is the throat-cancer risk higher in men, noted Gillison, but if you add HPV-associated throat, anal and penile cancers, the virus causes as many cancers in men as women.

Effective for men

The vaccine, known as Gardasil, is approved only for females 11 and older. There have been some studies done with males, but they have not been analyzed.

Gillison said she doesn't see any reason why the vaccine wouldn't be effective for throat cancers or men.

"Partners of women who have abnormal Pap smears should be aware they're at risk," Sturgis said. "They should refrain from oral sex until the matter is resolved."

Sturgis said M.D. Anderson is working on similar research it hopes to publish.

There are 11,000 HPV-associated cases of throat cancer a year, slightly more than the number diagnosed as cervical cancer. There is no simple swab test to indicate early onset of throat cancer. The treatment, surgery or intensive chemotherapy and radiation, is considered particularly difficult and causes speaking and eating problems.

Greatest risk factor

Gillison's team took blood and saliva samples from 100 patients with throat cancer — 86 males and 14 females — and 200 healthy people. They also collected information about participants' sexual history.

The study found people who had a prior infection with HPV were 32 times more likely to have throat cancer than those with no evidence of having the virus. Those who tested positive for a particularly aggressive strain, HPV-16, were 58 times more likely.

The virus was transmitted by both fellatio and cunnilingus. Most of the participants were married heterosexuals.

HPV is ubiquitous, infecting men and women in equal numbers. Gillison said one study has found that, at any time, 10 percent of women have it.

Gillison had conducted previous research showing an association between oral sex, HPV and cancer but wanted to know whether those cases were a fluke. The study, she said, found HPV was the greatest risk factor, dwarfing the contribution of alcohol and tobacco. Gillison said she expects in time HPV-associated oral cancers will outpace those caused by alcohol and tobacco use.

The same issue of the New England Journal featured two large studies demonstrating Gardasil is almost 100 percent effective in preventing cervical cancer. The studies, involving nearly 18,000 girls and women, found Gardasil is much more effective when given before women become sexually active.